engleski

Energy expenditure at the gait transition speed in men amd women

When increasing or decreasing the speed of locomotion, spontaneous transition occurs (walk-to-run, or run-to-walk) at approximately the same speed for both genders (2 m/s), and this intensity is commonly referred to as the preferred transition speed (PTS) (Hreljac, 1993). There are no data in the literature regarding the relative energy expenditure at the PTS, i.e. expressed in relation to the aerobic capacity, and eventual gender differences. The aim of this study was to relate the energy expenditure for walking and for running at the PTS to the aerobic capacity, and to determine gender differences. Twenty-two male (21.4 +/-2.4y, 182 +/- 7cm), and eleven female (19.4 +/- 0.5y, 169 +/- 6cm) physical education students performed two incremental treadmill tests with 4-min stages, walking in one and running in the other, in order to determine steady-state VO2 at speeds below and above PTS (5-9 km/h). A treadmill test to volitional exhaustion was performed for VO2max determination, and a fourth treadmill test was also performed at all subjects, in order to determine their individual PTS. The preferred gait transition speed did not differ between male (7.13 +/- 0.4 km/h) and female (7.21 +/- 0.3 km/h) subjects, as did not the corresponding energy expenditures for walking (24.3 +/- 3.6 and 26.6 +/- 3.7 ml O2/min/kg, p>0.05), and for running (29.5 +/- 2.6 and 31.3 +/- 2.9 ml O2/min/kg, p>0.05). Men had a significantly higher VO2max than women (50.8 +/- 4.7 vs. 44.9 +/- 4.0 ml O2/min/kg, p<0.01), while the oxygen uptake at the PTS expressed as a percentage of VO2max, was significantly higher for women, for walking (59 +/- 6% vs. 48 +/- 6%, p<0.01) as well as for running (70 +/- 6% vs. 58 +/- 6%, p<0.01). The average values for the PTS are in close agreement with previous studies. There is no experimental evidence that can explain why women change gait at the same speed as men ; no difference between the PTS of male and female subjects probably reflects the pressure of natural selection, that has favored the developement of the same average value for the gait transition speed in spite of significant gender differences in stature, mass and aerobic capacity. Anthropometric, morphological and biomechanical variables will be examined in follow-up studies to elucidate how women make better use of the limited energy sources, having a wider relative range of energy expenditure for walking. References. 1. Hreljac, A (1993). Preferred and ... Med Sci Sports Exerc 25(10):1158-62.

energy expenditure ; gait transition speed ; gender differences

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